BioExplorer Heart Rate Variability Designs

This suite includes more than 10 designs for biofeedback based on Heart Rate Variability and Heart Rate Coherence.

Heart Rate Coherence is a beneficial oscillation in Heart Rate (HR) which is synchronised with breathing. High coherence is associated with relatively large "amplitude" changes in HR over the cycle of each breath, where the "amplitude" is stable or consistent of a sequence of breaths.

Many of the designs are based on an innovative algorithm, which relates HR to breathing and generates a coherence "score" in the range 0-100. (More details of the algorithm are given in the User Guide.)

Features

• HR calculation is based on EKG or electrocardiogram. (Note that many amplifiers designed for EEG work can record an adequate EKG signal.)
• HR calculation has basic artefact rejection built in.
• Breathing can be measured using either temerature (of inhaled/exhaled air) or pneumograph (strain gage). There are two functionally equivalent design sets based on each breath parameter.
• Robust, stable detection of breath turning points, giving derived measures such as breathing rate and ratio of inhalation to exhalation duration.
• Adjustable sensitivity - increasing the sensitivity makes it easier for the trainee to achieve a high coherence score.
• 2 screens - one for checking signals and setting feedback options, the other for visual feedback.

Graphical Feedback Features

• 2 minute trend displaying HR and breathing together
• 
• 2 minute trend displaying coherence score, in parallel with HR / breathing
• 
• long term (20 minute) trend displaying coherence score + breathing rate
• 
• Spectral analysis of raw EKG
• 

Audio Feedback Features

Each audio feedback option can be switched on and off using a button.

• HR Midi - plays a note for each heart beat, whose pitch is determined by HR (or interval since the previous beat).
• Threshold-based feedback - sounds for sudden changes in coherence score
• Threshold-based feedback - sounds when breathing rate drifts out of range.
• Tone feedback of coherence score (variable pitch)

Video Feedback

One of the designs uses the Video Player object as the principle vehicle for feedback. Here, the forward motion of the video is constrained by the coherence score in relation to a double threshold - forward motion stops at the lower threshold and reaches a maximum speed at the upper threshold. When coherence drops below the lower threshold, the video will either remain stationary or move backwards, depending on the state of an option button. There is accompanying audio feedback.

DVD Feedback

Another designs uses the DVD Player as the main form of feedback. Again feedback is constrained by the coherence score in relation to a double threshold. When coherence drops below the upper threshold, the picture quality degrades by either "greying out" or by shrinking, reaching a peak at the lower threshold. Sound quality is also degraded. Conversely, when the signal moves in the "right" direction, the picture is unimpeded.

Sample Screenshots

Click on the thumbnail to see the full-scale image.

	1. Coherence Design Notice the relatively sudden drop-off in coherence score at the point where the breath de-synchronises from the heart wave. You can see from the long-term trend that this has happened a total of five times.
	2. Coherence Design with EKG Spectrum In this example you see a loss of coherence as the breathing shifts to a more rapid pace.
	3. Video Design Here the video is the principle mode of feedback but you also see the heart wave and coherence score. Note the layout of the DVD design is substantially the same. A dual screen version shows only the video display in the client's screen.

For further information see the User Guide for the Heart Rate Variability designs. This can be downloaded for free. Visit the downloads page by clicking the link in the navigation menu.

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